panel data- non continous period

[seridevie]

Hi

I am just wondering whether the panel time period should be in continous order, i.e year: 2000 to 2004. My data is based on 200 cross section but not with continous year,i.e 2000 2001 and 2008. Is there any effect on the validity of the estimates or any other problems?

Note: This is a pre and post effect of policy introduction on the independent variables.

Cheers
Seri